1. Field of the Invention
The present invention relates to a signal output apparatus. The present invention also relates to a detection apparatus detecting information about sheet materials for use in an image forming apparatus, a sheet conveying apparatus and the like, and an image forming apparatus comprising such a detection apparatus, and so on.
2. Related Background Art
In recent years, the types of printing sheets are being diversified for use in an image-forming apparatus such as copying machines and printers. With such trend, apparatuses for identifying the type of a sheet material are attracting attention.
A method of determining the type of sheet material is described in Japanese Patent Application Laid-Open No. H11-314443 (U.S. Pat. No. 6,097,497).
In the technique disclosed in the above patent publications, a numeral code or a symbol is attached preliminarily as a mark to the sheet material (hereinafter referred to as a “marking system”), and the information of the mark is read by a sensor equipped in a printer or a copying machine to select an optimum printing mode by utilizing the read information.
In the aforementioned marking system, the type of the sheet cannot be identified without the code or symbol attached thereto.
The present invention intends to provide an apparatus for identifying the type of a sheet material, being capable of outputting information on the type of the sheet material regardless of the presence or absence of the marked information attached to the sheet material.